Detection and mitigation of interference based on interference location

Abstract

Embodiments include a novel receiver architecture to optimize receiver performance in the presence of interference. In various embodiments, the presence of interference is detected, and the relative frequency location of the interference is detected. The relative frequency location specifies whether the frequency of the interference is high side (above the desired signal, i.e., at a higher frequency) or low side (below the desired signal). The receiver is configured based on the detected interference and relative location thereof. For a device such as a cellular phone that operates in a dynamic and changing environment where interference is variable, embodiments advantageously provide the capability to modify the receiver's operational state depending on the interference.

What is claimed is: 
     
       1. A method comprising:
 receiving a filtered signal; 
 detecting, based on the filtered signal, a relative frequency location of an interference signal; 
 generating a feedback signal based on the detected relative frequency location, and 
 updating an oscillator signal based on the feedback signal, to cause a shift in energy in the input signal away from the detected frequency location. 
 
     
     
       2. The method of  claim 1 , wherein detecting the relative frequency location of the interference signal includes:
 shifting the filtered signal, directly or after additional filtering or amplification, by a predetermined offset in a first direction, to provide a low side shifted signal; 
 low pass filtering the low side shifted signal, to provide a low pass filtered low side signal; 
 measuring power of the low pass filtered low side signal, to provide a low side power measurement; 
 shifting the filtered signal, directly or after additional filtering or amplification, by the predetermined offset in a second direction opposite the first direction, to provide a high side shifted signal; 
 low pass filtering the high side shifted signal, to provide a low pass filtered high side signal; 
 measuring power of the low pass filtered high side signal, to provide a high side power measurement; and 
 comparing a predetermined threshold and at least one of the low side power measurement and the high side power measurement. 
 
     
     
       3. The method of  claim 2 , wherein updating the oscillator signal includes updating the oscillator signal to cause the input signal to be shifted higher in frequency, when the high side power measurement is greater than the predetermined threshold. 
     
     
       4. The method of  claim 2 , wherein updating the oscillator signal includes updating the oscillator signal to cause the input signal to be shifted lower in frequency, when the low side power measurement is greater than the predetermined threshold. 
     
     
       5. The method of  claim 2 , wherein updating the oscillator signal includes updating the oscillator signal to cause the input signal to be neither shifted higher nor lower in frequency, when the high side power measurement and the low side power measurement are greater than the predetermined threshold. 
     
     
       6. The method of  claim 1 , wherein detecting the relative frequency location of the interference signal includes:
 performing a fast Fourier transform (FFT) on the filtered signal, directly or after additional filtering or amplification to provide a frequency domain signal; 
 comparing a predetermined threshold and at least one of the frequency domain signal at a first frequency bin, corresponding to a predetermined frequency magnitude and a first sign, and the frequency domain signal at a second frequency bin, corresponding to the predetermined frequency magnitude and a second sign opposite the first sign. 
 
     
     
       7. The method of  claim 6 , wherein the feedback signal is configured to cause the updated oscillator signal, provided to a mixer, to shift the input signal higher in frequency, when the frequency domain signal at the first frequency bin is greater than the predetermined threshold. 
     
     
       8. The method of  claim 6 , wherein the feedback signal is configured to cause the updated oscillator signal, provided to a mixer, to shift the input signal lower in frequency, when the frequency domain signal at the second frequency bin is greater than the predetermined threshold. 
     
     
       9. The method of  claim 6 , wherein the feedback signal is configured to cause the updated oscillator signal, provided to a mixer, to neither shift the input signal higher nor lower in frequency, when the frequency domain signal at the first and second frequency bins is greater than the predetermined threshold. 
     
     
       10. An interference frequency detection (IFD) module comprising:
 a low side mixer configured to shift an input of the IFD module by a predetermined offset in a first direction; 
 a first low pass filter configured to filter an output of the low side mixer; 
 a low side power estimation circuit configured to measure power at an output of the first low pass filter; 
 a high side mixer configured to shift the input of the IFD module by the predetermined offset in a second direction opposite the first direction; 
 a second low pass filter configured to filter an output of the high side mixer; 
 a high side power estimation circuit configured to measure power at an output of the second low pass filter; and 
 a comparator configured to output an IFD output signal based on a comparison between a predetermined threshold and at least one of an output of the low side power estimation circuit and an output of the high side power estimation circuit. 
 
     
     
       11. The IFD module of  claim 10 , wherein updating the oscillator signal includes updating the oscillator signal to cause the input signal to be shifted higher in frequency, when the high side power measurement is greater than the predetermined threshold. 
     
     
       12. The IFD module of  claim 10 , wherein updating the oscillator signal includes updating the oscillator signal to cause the input signal to be shifted lower in frequency, when the low side power measurement is greater than the predetermined threshold. 
     
     
       13. The IFD module of  claim 10 , wherein updating the oscillator signal includes updating the oscillator signal to cause the input signal to be neither shifted higher nor lower in frequency, when the high side power measurement and the low side power measurement are greater than the predetermined threshold. 
     
     
       14. The IFD module of  claim 10 , further comprising:
 a detector configured to detecting a relative frequency location of the interference signal by performing a fast Fourier transform (FFT) on the filtered signal, directly or after additional filtering or amplification to provide a frequency domain signal, and comparing a predetermined threshold and at least one of the frequency domain signal at a first frequency bin, corresponding to a predetermined frequency magnitude and a first sign, and the frequency domain signal at a second frequency bin, corresponding to the predetermined frequency magnitude and a second sign opposite the first sign. 
 
     
     
       15. The IFD module of  claim 14 ,
 wherein a state machine is coupled to the output of the IFD module, the state machine is configured to provide a feedback signal, based on the IFD output signal, for causing a shift in energy in an input signal of the filter away from the detected frequency location. 
 
     
     
       16. The IFD module of  claim 14 ,
 wherein the feedback signal is configured to cause the updated oscillator signal, provided to a mixer, to shift the input signal higher in frequency, when the frequency domain signal at the first frequency bin is greater than the predetermined threshold. 
 
     
     
       17. The IFD module of  claim 14 , wherein the feedback signal is configured to cause the updated oscillator signal, provided to a mixer, to shift the input signal lower in frequency, when the frequency domain signal at the second frequency bin is greater than the predetermined threshold. 
     
     
       18. The IFD module of  claim 14 , wherein the feedback signal is configured to cause the updated oscillator signal, provided to a mixer, to neither shift the input signal higher nor lower in frequency, when the frequency domain signal at the first and second frequency bins is greater than the predetermined threshold. 
     
     
       19. An apparatus comprising:
 an interference frequency detection (IFD) module configured to receive a filtered signal, to detect, based on the filtered signal, a relative frequency location of an interference signal, to provide an IFD output signal indicative of the detection result at an output of the IFD module; and 
 a state machine, coupled to the output of the IFD module configured to generate a feedback signal based on the detected relative frequency location, and to update an oscillator signal based on the feedback signal, to cause a shift in energy in an input signal away from the detected frequency location. 
 
     
     
       20. The apparatus of  claim 19 , the IFD module comprising:
 a low side mixer configured to shift an input of the IFD module by a predetermined offset in a first direction; 
 a first low pass filter configured to filter an output of the low side mixer; 
 a low side power estimation circuit configured to measure power at an output of the first low pass filter; 
 a high side mixer configured to shift the input of the IFD module by the predetermined offset in a second direction opposite the first direction; 
 a second low pass filter configured to filter an output of the high side mixer; 
 a high side power estimation circuit configured to measure power at an output of the second low pass filter; and 
 a comparator configured to output an IFD output signal based on a comparison between a predetermined threshold and at least one of an output of the low side power estimation circuit and an output of the high side power estimation circuit.